Background: The development of resistance by pathogenic microorganisms has renewed the
worldwide search for novel antimicrobial agents. Mushrooms are of recent interest because a wide variety
of biologically active compounds have been isolated from them. This study isolated antimicrobial
compound from two wood decaying mushrooms, Trametes gibbosa and Trametes elegans, and determined
the resistance modifying activities of the isolated compound.
Methods: Bioactivity guided isolation of active principles from the methanol extract of T. gibbosa and
T. elegans was performed using column and preparative high-performance liquid chromatography. The
structures of isolated compounds were elucidated using nuclear magnetic resonance spectroscopy. Broth
micro-dilution assay was used to determine the antimicrobial and resistance modifying activities of the
isolated compounds against Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Salmonella
typhi, Streptococcus pyogenes, Staphylococcus aureus, Enterococcus faecalis, Bacillus subtilis, Candida
albicans, Aspergillus niger, Aspergillus flavus and Aspergillus tamarii.
Results: Bioactivity guided isolation lead to the isolation of cerevisterol (ergosta-7, 22E-diene-3β5α, 6β-
triol) from both T. gibbosa and T. elegans. The isolated cerevisterol inhibited the growth of S. typhi, S.
aureus and A. niger with MICs of 25 µg/mL each and 50 μg/mL against E. faecalis. The MBCs of
cerevisterol against S. typhi S. aureus, E. faecalis and A. niger were 50, 100, 200 and 100 µg/mL, respectively.
The sub-inhibitory concentration (3 µg/mL) of cerevisterol modified the activity of erythromycin,
ampicillin, ciprofloxacin, tetracycline and amoxicillin either by potentiating or reducing their activities.
Conclusion: Cerevisterol possesses both antimicrobial and resistance modifying activities.